Association Between Urinary Arsenic Level And Mild Cognitive Impairment Among The Elderly In Fuyang City

BackgroundAs a country with the largest elderly population,Mild Cognitive Impairment(MCI)has become a major public health problem in China.There is no effective treatment for MCI.Therefore,it is very important to identify the risk factors of MCI to prevent or delay the occurrence of MCI.The cause of MCI is not fully understood.Studies have shown that environmental factors such as heavy metals are closely related to the occurrence of MCI.As a metal-like element with strong toxicity,arsenic has significant influence on MCI.Although more and more evidence suggests that arsenic exposure may harm the cognitive function of the elderly,the current research results are inconsistent or controversial.Therefore,whether there is a correlation between urinary arsenic level and MCI in the elderly and the strength of the correlation need to be further studied.ObjectiveThe aim of present study was to investigate urinary arsenic level and MCI in elderly in Fuyang city,Anhui province,China,and to investigate the association between urinary arsenic level and MCI.MethodsFrom June to August 2018,a total of 6000 elderly aged 60 or above were sampled by Probability Proportionate to Size Sampling(PPS)in eight counties or districts in Fuyang city,Anhui province,for questionnaire survey,physical examination and urine sample collection.The Mini-mental State Examination(MMSE)was used to collect the cognitive status of the Community Dwelling Elderly.Arsenic concentrations in urine were measured using an Inductively Coupled Plasma Mass Spectrometer(ICP-MS).Binomial logistic regression model was used to analyze the association between urinary arsenic level and MCI,and stratified analysis was performed by gender and age.The dose-response relationship between urinary arsenic level and MCI was analyzed by restrictive cubic spline curve.ResultsAccording to the purpose of this study,we selected 3811 subjects aged 60 years or above with the enrolled elderly(n=6000)after excluding 2189 because of missing questionnaire information(n=421),missing physical examination(n=393),missing MMSE entry(n=296),and no morning urine(n=1079).In this study,1,152 elderly had MCI,accounting for 30.2% of the total population.The detection rate of arsenic in urine was 100%.The geometric concentration of arsenic in the total population was 15.85?g/L,the median value was 15.79?g/L,and the maximum value was 532.66?g/L.Single factor logistic regression analysis showed that,the prevalence of MCI in the elderly exposed to medium(13.93?24.12?g/g)levels of arsenic was higher(OR=1.12,95% CI: 0.94?1.32)than the elderly exposed to low levels of urinary arsenic(<13.92?g/g),but the association was not statistically significant.The odds of MCI was 1.23 times higher in older adults with high arsenic exposure(>24.13?g/g)than those exposed to low levels of urinary arsenic(OR =1.23,95% CI: 1.04?1.46).After adjusting for the general demographic variables(gender,age,area,county,education,occupation,marital status,and family monthly income),there was no statistically significant correlation between median arsenic exposure and MCI(OR =1.13,95% CI: 0.94?1.35).High arsenic exposure was statistically associated with MCI(OR =1.26,95% CI: 1.05?1.51).After further adjustment of smoking status,drinking status,and dietary pattern(animal model,sugar and lipid model,vegetable model,viscera and animal oil model),hypertension,coronary heart disease,daily activity capacity and depression status,the association between moderate arsenic exposure and MCI was not significant,in contrast,the association of high arsenic exposure with MCI remained significant(OR=1.28,95%CI: 1.04?1.57).The results of stratified analysis by gender and age showed that,after adjusting for demographic variables(gender,age,area,county,education,occupation,marital status,family monthly income),smoking status,alcohol consumption status,diet pattern(animal model,sugar and lipid model,coarse grain and vegetable model,viscera and animal oil model),hypertension,coronary heart disease,daily activity capacity and depression status,the prevalence of MCI increased by 37%(OR=1.37,95%CI:1.03?1.81)in older adults with high arsenic exposure compared with the low-exposure group among women,the prevalence of MCI increased by 45%(OR=1.45,95%CI:1.10?1.90)in the elderly with high arsenic exposure compared to the low-exposure group among 70-97 age group.But the association was not statistically significant in men or in the 60-69 age group.The dose-response curve also showed a linear dose-response over a certain concentration range between the urinary arsenic level and MCI.ConclusionsResults from this study showed a significant association between urinary arsenic level and MCI,approximately with a linear dose-response over a certain concentration range.The association was stronger in women,but not in men and in older adults,but not in younger adults.